3.1.2 God, the One
Belief in God as the One God is one of the fundamental professions of both the Old and New Testaments. God Himself spoke to Moses of His oneness and faithfulness to Himself, which is expressed in His name: "I AM WHO I AM" (Exodus 3: 14). The profession of God's uniqueness–"Hear, O Israel: The Lord our God, the Lord is one!" (Deuteronomy 6: 4)–remained with the people of the old covenant throughout their entire history.
Although already stated unequivocally in the First Commandment–"You shall have no other gods before Me" (Exodus 20: 3)–it was a long time before Israel professed the uniqueness of God to the exclusion of all other gods and their worship. Again and again, the prophets had to reproach the people for worshipping other gods. In Isaiah 45: 21-22, we find the words of God: "And there is no other God besides Me, a just God and a Saviour; there is none besides Me. Look to Me, and be saved, all you ends of the earth! For I am God, and there is no other." After their return from Babylonian captivity, profession of the one God (monotheism) entered into the consciousness of the Jews as the essential distinguishing feature between them and the Gentiles. To this day, the belief expressed in the Wisdom of Solomon has been a distinguishing feature of Judaism: "For neither is there any God but [Thee]" (Wisdom of Solomon 12: 13).
This profession is also firmly rooted in Christian faith, from the earliest apostolic congregations until the present. Apostle Paul advocated monotheism without restrictions of any kind. With a view to the polytheism of the Greek and Roman religions, he wrote: "Therefore ... we know that ... there is no other God but one" (1 Corinthians 8: 4).